Power distribution system and method thereof in which redundant power is collected only when power pool is below or equal to pool threshold

ABSTRACT

A power distribution system is adapted to a management module connected to a plurality of servers, each of which is varied in power consumption in response to a power mode and performance thereof, via a power allocation request line and a power allocation response line. The management module records the upper-limit power setting, the power allocations, and the power pool with regard to the servers. The server records the power mode, the power allocation, the upper mode request threshold, and the redundant power which is calculated based on the difference between the power allocation and the actual power consumption. The management module recovers the redundant power from the server so as to update the power pool. Upon receiving a power allocation request, the management module distributes at least a part of the power pool to the server, thus allowing the server to shift the power mode to the upper mode.

The present application claims priority on Japanese Patent ApplicationNo. 2009-34051, the content of which is incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to power distribution systems and methodsfor allocating electric power to information processing apparatuseswithin limited available electricity.

DESCRIPTION OF THE RELATED ART

In computer systems, limited available electricity is shared andallocated to servers in such a way that power allocations which are notcurrently used in servers are pooled as reserve power, which areappropriately and rapidly allocated to other servers requiring power.

Power distribution systems may hardly follow up with rapidly increasingpower consumptions exploited in information-technology (IT) apparatusesbecause of insufficient installation environments and delayed budgetallotments with regard to electrical facilities. It is a pressing needto develop sophisticated power distribution systems to cope withinsufficient installation environments of IT apparatuses and limitedavailable electricity.

For this reason, various technologies have been developed with respectto power management systems adapted to computers and informationprocessing apparatuses.

-   -   Patent Document 1: Japanese Patent Application Publication No.        2006-11793    -   Patent Document 2: Japanese Patent Application Publication No.        2006-195986

The power management systems disclosed in Patent Documents 1 and 2 needa long time for allocating power to information processing apparatuses.Delayed power allocation may cause unwanted processing losses due torapid variations of power caused by information processing apparatuses.Inefficient power allocation may degrade the entire system performance.

Presumably, the overall time required for processing power allocationstends to increase due to the following problems.

-   (1) Every time each server requests a power allocation, it is    necessary to limit the allocated power of another server (already    sufficing its operation) so as to reserve a redundant power.-   (2) It is necessary to perform negotiations over power distributions    via networks such as local area networks (LAN).

SUMMARY

The present invention seeks to solve the above problems, or to improveupon the problems at least in part.

The present invention is directed to a power distribution system andmethod adapted to a management module connected to a plurality ofinformation processing apparatuses (e.g. servers), each of which isvaried in power consumption in response to a power mode and performancethereof, via a network.

As to the problem (1), the present invention recovers the redundantpower from servers in advance by way of the power pool so that thenecessary amount of power can be immediately distributed to each serverupon receiving a power allocation request. Herein, the server normallymonitors and updates the redundant power corresponding to the differencebetween the power allocation and the actual power consumption thereof,thus enabling the management module to recover the redundant power atany time. The management module is able to designate the server forrecovering its redundant power on the basis of the predeterminedpriority or in light of the predetermined policy in which the managementmodule does not recover the redundant power for a certain time period,thus coping with load variations.

As to the problem (2), the present invention introduces hard-wiredinterrupt lines (e.g. a power allocation request line and a powerallocation response line laid between the management module and theserver), so as to reduce the overall time required for processing powerallocations. Specifically, the server uses the power allocation requestline to interrupt the management module upon requesting a powerallocation thereto. The management module uses the power allocationresponse line to accept or reject the power allocation request by way of“acknowledge (Ack)” or “Non-Acknowledge (Nak)”. Upon receiving the powerallocation request, the management module determines whether or not thepower pool thereof suffices the maximum power requested by the server,thus returning “Ack/Nak” to the server. Thus, the server receiving “Ack”is able to exploit the power pool of the management module.

The present invention demonstrates the following effects.

-   (1) The management module is designed to arbitrarily recover    redundant power and to reserve the power pool by way of the    background operation in connection with the servers, so that an    adequate amount of power can be immediately retrieved from the power    pool and distributed to the server upon receiving a power allocation    request. This eliminates the necessity of performing complicated    procedures in which upon receiving a power allocation from a certain    server, the management module retrieves power allocations from other    servers; hence, it is possible to reduce the overall time required    for processing power allocations to servers.-   (2) It is possible to significantly reduce the overall time required    for processing power allocations to servers by use of communication    lines exclusively used for transmitting power allocation requests    and responses between the management module and servers.-   (3) Due to the above effects (1) and (2), it is possible to reduce    the time required for processing power allocation to a front-end    server (e.g. a WEB server), which presumably undergoes rapid load    variations, thus roughly eliminating the performance loss caused by    the time-consuming power allocation processing.-   (4) The present invention does not allow the management module to    recover redundant power from servers when the power pool exceeds the    pool threshold. This prevents the management module from excessively    recovering redundant power from servers even when the power pool    adequately suffices the total power consumption made by grouped    servers. This also prevents servers from being degraded in    performance due to unnecessary limitations imposed on functions of    servers.-   (5) Using the power allocation request/response lines each    configured of multiple bits, the management module is able to    perform fine adjustment on power allocations to servers, since the    power allocation to each server is not necessarily controlled in    simple on/off states. This contributes to a reduction of the time    required by each server shifting its power mode to an optimum mode.-   (6) Through adjusting the power monitor time in which the server    monitors the actual power consumption for the purpose of calculating    the redundant power, it is possible to designate an optimum policy,    which allows the management module to recover redundant power from    each server in response to its job, in a flexible manner For    example, the power monitor time is increased with respect to a    database server, which does not undergo large power variations, so    as to prevent the power allocation from being frequently retrieved    in response to subtle power variations. Alternatively, the power    monitor time is decreased with respect to a WEB server, which    readily undergoes power variations, so as to efficiently recover    redundant power.

BRIEF DESCRIPTION OF THE DRAWINGS

The above features and advantages of the present invention will be moreapparent from the following description of certain preferred embodimentstaken in conjunction with the accompanying drawings.

FIG. 1 is a block diagram showing the constitution of a powerdistribution system including a management module and a plurality ofservers in accordance with a preferred embodiment of the presentinvention.

FIG. 2 shows the details of a power mode management table included ineach server whose power allocation is managed by the management module.

FIG. 3 shows the details of a power allocation/management table includedin the management module.

FIG. 4 is a graph showing the relationship between the power pool andthe sum of power allocations to servers.

FIG. 5 is a flowchart showing a sequence for updating recoverableredundant power.

FIG. 6 shows a power recovery sequence in which the management modulerecovers a redundant power from the server.

FIG. 7 shows an acceptance mode of a power allocation request sequencein which the management module accepts a power allocation request madeby the server.

FIG. 8 shows a rejection mode of the power allocation request sequencein which the management module rejects the power allocation request madeby the server.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will be now described herein with reference toillustrative embodiments. Those skilled in the art will recognize thatmany alternative embodiments can be accomplished using the teachings ofthe present invention and that the invention is not limited to theembodiments illustrated for explanatory purposes.

FIG. 1 is a block diagram showing the constitution of a powerdistribution system according to a preferred embodiment of the presentinvention. The power distribution system of FIG. 1 includes a managementmodule 101 connected to a plurality of servers 201-1, 201-2, 201-3, . .. (simply, referred to as servers 201). The management module 101 andthe servers 201 are each configured using a computer, for example. Themanagement module 101 manages power consumption with regard to theservers 201. The servers 201 are aggregated together as a server group202. The management module 101 is connected to each server 201 via apower allocation request line 301 and a power allocation response line302. The management module 101 and the servers 201 are all connected toa network 303.

The management module 101 is constituted of a storage unit 110, acontrol arithmetic unit 111, a power allocation request acceptance unit112, a communication unit 113 and a user interface 125. The storage unit110 stores an upper-limit power setting 121, a powerallocation/management table 122, a power pool 123, and a pool threshold124. The storage unit 110 is constituted of a memory, a hard-disk unit,and the like. The control arithmetic unit 111 is configured of a CPU,for example.

The power allocation/management table 122 records power allocations tothe servers 201. The upper-limit power setting 121 indicates theupper-limit value of power allocated to the server group 202 in total.The management module 101 allows the user to freely modify theupper-limit power setting 121 via the user interface 125.

The management module 101 allocates power to the servers 201 within theupper-limit power setting 121. The management module 101 manages powerallocations to the servers 201 with reference to the powerallocation/management table 122. The sum of power allocations to theservers 201 cannot exceed the upper-limit power setting 121. Thedifference between the upper-limit power setting 121 and the sum ofpower allocations is defined as the power pool 123. When the power pool123 becomes lower than the pool threshold 124, the management module 101recovers a redundant power.

Each server 201 is constituted of a storage unit 210, a communicationunit 211, a control arithmetic unit 213, a power sensor 214, and a powerallocation request unit 218. Each server 201 includes power-consumingcomponents such as a processor 221 a, a memory 221 b, a chip set 221 c,and a disk drive 221 d. These components can be limited in performancein response to a power mode change instruction from the controlarithmetic unit 213, so that they can consume limited power sufficinglimited performance. The power sensor 214 normally monitors actual powerconsumption of each server 201.

The storage unit 210 records a power mode management table 212, a powerallocation 215, a redundant power 216, a power monitor time 217, a powermode 219, a recoverable redundant power 220, and a power monitor value222. The storage unit 210 is constituted of a memory, a hard-disk unit,and the like. The control arithmetic unit 213 is configured of a CPU,for example.

The power mode management table 212 records a maximum power at eachpower mode, an upper mode request threshold, and a mapping involved inperformance-limiting factors of components. In the server 201, the powermonitor value 222 does not exceed the maximum power at one mode. Whenthe power monitor value 222 exceeds the upper mode request threshold atone mode, the server 201 is shifted from one mode to the upper mode,thus requesting an additional power allocation.

FIG. 2 shows the details of the power mode management table 212, whichdescribes a plurality of power modes (i.e. Mode 1, Mode 2, . . . , Moden) in connection with each server 201. Upper modes need higher powerconsumption, while lower modes need smaller power consumption. The powerallocation/recovery is achieved by changing the power mode of eachserver 201. Each mode stipulates the maximum power; hence, each server201 operates so as not to exceed the maximum power at each mode. Thisoperation is implemented by mapping performance-limiting factors ofcomponents in connection with power modes. Herein, each component iscontrolled to operate with the preset performance-limiting factor ateach mode. The relationship between the mapping and the maximum power isactually measured in advance.

The power mode management table 212 records the upper mode requestthreshold as well. When the power monitor value 222 exceeds the uppermode request threshold, each server 201 being shifted from one mode tothe upper mode requests the management module 101 to designate anadditional power allocation.

Each server 201 has the “private” power sensor 214 for measuring theentire power consumption thereof. Through monitoring the actual powerconsumption of each server 201 within the power monitor time 217, thepower sensor 214 detects the maximum power as the power monitor value222. It is possible to eliminate the power monitor time 217 so that eachserver 201 detects the actually monitored power consumption as the powermonitor value 222, which is recorded in the storage unit 210. Inaddition, the storage unit 210 records the power allocation 215 which isdesignated for each server 201 by the management module 101. Themanagement module 101 allows the user to arbitrarily modify the powermonitor time 217 recorded in the storage unit 210 within a certainrange.

FIG. 3 shows the details of the power allocation/management table 122,which records power allocations with respect to the servers 201.

FIG. 4 shows the relationship between the upper-limit power setting 121,the power pool 123, and the sum of power allocations to the servers 201.The remainder calculated by subtracting the sum of power allocationsfrom the upper-limit power setting 121 corresponds to the power pool123. When the power pool 123 becomes lower than the pool threshold 124,the management module 101 requests the servers 201 to recover redundantpower.

The power allocation request unit 218 of each server 201 is connected tothe power allocation request acceptance unit 112 of the managementmodule 101 via the 1-bit power allocation request line 301 and the 1-bitpower allocation response line 302. A power allocation request signal issent from the server 201 to the management module 101 via the powerallocation request line 301, while a power allocation response signal issent from the management module 101 to the server 201 via the powerallocation response line 302. The present embodiment achieves high-speedpower allocation using the power allocation request line 301 and thepower allocation response line 302. In order to achieve high-speedprocessing of power allocation, the power allocation request acceptanceunit 112 and the power allocation request unit 218 are configured usingoptimal combinations of electronic circuits. In this connection, thepower allocation response line 302 can be configured of multiple bits.

The management module 101 and the server 201 are able to communicatewith each other by use of the communication units 113 and 211 installedtherein.

It is possible to arrange a plurality of management modules (instead ofa single management module 101), thus achieving a certain redundancy inmanaging power allocations to servers. Even when one management moduleis down, another management module compensates for its function so as tocontinue processing in managing power allocations to servers.

Alternatively, it is possible to select one of the servers 201 as amanagement module. Herein, the selected server 201 serving as themanagement module performs power management on the server group 202thereof.

The present embodiment does not necessarily perform power management onthe servers 201; that is, it is able to perform power management onother information processing apparatuses such as storage devices andswitching devices. That is, the application of the present embodimentcan be expanded to handle any types of information processingapparatuses having mechanisms for establishing transactions regardingpower allocations via the power allocation request line 301, the powerallocation response line 302, and the network 303.

FIG. 5 shows a sequence for updating the recoverable redundant power 220in the server 201. In step S51, the power sensor 24 monitors the actualpower consumption during the power monitor time 217 so as to detect themaximum value as the power monitor value 222. At this time, theredundant power 216 is calculated by subtracting the power monitor value222 from the power allocation 215. When the server 201 determines instep S52 that the power monitor value 222 is lower than the maximumpower of a lower mode lower than the “present” power mode 219, the flowproceeds to step S53 in which the recoverable redundant power 220 iscalculated by subtracting the maximum power of the lower mode from thepower allocation 215 (corresponding to the maximum power of the presentpower mode 219). The server 201 repeats the above procedure.

The power monitor time 217 is determined to suit the type of jobexecuted by each server 201. In the case of a database server havingsmall power variations, for example, the power monitor time 217 isincreased so as to prevent power from being frequently recovered due tosensitive response to small power variations. In the case of a WEBserver, the power monitor time 217 is decreased so as to efficientlyrecover power.

FIG. 6 shows a power allocation request sequence which is initiated whenthe management module 101 recovers a redundant power from the server201. When the power pool 123 becomes lower than the pool threshold 124,the management module 101 makes a redundant power recovery request tothe server 201 in step S-21. That is, the management module 101 issues apower recovery request packet toward the server 201 via the network 303in step S-22.

The server 201 periodically updates the recoverable redundant power 220based on the power monitor value 222 (indicating the actual powerconsumption) and the power allocation 215 ascribed to the present powermode 219.

Upon receiving the power recovery request packet, the server 201confirms whether or not the recoverable redundant power 220 remainstherein in step S-23. When the recoverable redundant power 220 remains,the server 201 changes the power mode 219 to a lower mode whose maximumpower matches a reduction of the recoverable redundant power 220, thuscorrespondingly updating the power allocation 215 in step S-24. Then,the server 201 sends back a power recovery response packet including theinformation of the recoverable redundant power 220 to the managementmodule 101 in step S-25. Upon receiving the power recovery responsepacket, the management module 101 updates the power allocation describedin the power allocation/management table 122. That is, the managementmodule 101 reduces the previous power allocation by the recoverableredundant power 220 with respect to the server 201 while increasing thepower pool 123 by the recoverable redundant power 220.

The management module 101 sequentially requests the servers 201 torecover power until the power pool 123 exceeds the pool threshold 124.If the power pool 123 does not exceed the pool threshold 124 even whenall the redundant power is recovered from the servers 201, themanagement module 101 continues to periodically request the servers 201to recover power.

The redundant power is not necessarily recovered at once from eachserver 201; that is, it is possible to recover power from the server 201at multiple times. In this case, the server 201 receiving a powerrecovery request packet from the management module 101 informs themanagement module 101 of a part of the recoverable redundant power 220.Upon receiving a power recovery response packet indicating a part of therecoverable redundant power 220 from the server 201, the managementmodule 101 continues sequentially requesting the servers 201 to recoverpower.

FIG. 7 shows an acceptance mode of a power allocation request sequence.In the server 201, the power sensor 214 normally monitors the actualpower consumption so as to update the power monitor value 222. In stepS-1, when the actual power consumption increases so as exceed the uppermode request threshold, the server 201 makes a power allocation requestto the management module 101. In step S-2, the server 201 asserts thepower allocation request line 301 connected to the management module101. At the same time, the server 201 sends the information regardingthe maximum power of the highest mode to the management module 101.

In step S-3, the management module 101 calculates the difference betweenthe maximum power of the highest mode and the maximum power of thepresent power mode 219 (i.e. the power allocation 215); then, itcompares the difference with the power pool 123. When the power pool 123is larger than the calculated difference, the management module 101makes an additional power allocation to the server 201.

In step S-4, the management module 101 updates the power allocation,which is described in the power allocation/management table 122 withrespect to the server 201, with the maximum power of the highest mode.In step S-5, the management module 101 asserts the power allocationresponse line 302 connected to the server 201 since it acknowledges thepower allocation request made by the server 201. At this time, themanagement module 101 subtracts a decrement (corresponding to anincrement of the power allocation to the server 201) from the power pool123. In step S-6, the server 201 raises the power mode 219 to thehighest mode in response to the asserting of the power allocationresponse line 302, wherein the server 201 updates the power allocation215 with the maximum power of the highest mode in the storage unit 210.In step S-7, the server 201 resets the power allocation request line301. In step S-8, the management module 101 correspondingly resets thepower allocation response line 302.

FIG. 8 shows a rejection mode of the power allocation request sequence,wherein the server 201 executes the steps S-1 and S-2 similarly to theacceptance mode of FIG. 7. In step S-9, the management module 101compares the power pool 123 with the difference between the maximumpower of the highest mode and the power allocation 215 of the presentpower mode 219 in the server 201. When the power pool 123 is lower thanthe difference, the management module 101 is unable to make anadditional power allocation to the server 201. In this case, themanagement module 101 does not assert the power allocation response line302 since it rejects the power allocation request made by the server201. Since the management module 101 does not assert the powerallocation response line 302 in a lapse of a predetermined time (seestep S-10), the server 201 determines that the power allocation requestis rejected by the management module 101; thus, the server 201 resetsthe power allocation request line 301 in step S-11.

When the management module 101 acknowledges a plurality of powerallocation request lines 301 being simultaneously asserted by theservers 201, the management module 101 makes an additional powerallocation to the designated server 201 in light of the redundancy ofthe power pool 123.

Using the power allocation response line 302 consisting of multiplebits, the management module 101 is able to cope with an additional powerallocation even when the power allocation to the server 201 cannot beincreased up to the maximum power of the highest mode, wherein the powermode 219 of the server 201 may be raised by one level, for example. Forinstance, when the power allocation response line 302 consists of threebits, a decimal value “0” of three-bit data is used to indicate “reset”,while “1” to “7” are used to indicate seven levels of power mode. Thisallows the management module 101 to arbitrarily select seven levels ofpower mode when increasing the power allocation to the server 201.

The present invention has a variety of industrial applications asfollows:

(1) Blade Server System

The package management module of the blade server system carries thefunction of the management module 101, wherein the entire package isregarded as the server group 202, and power management is performed suchthat the entire power consumption of the package does not exceed thepredetermined power. Herein, the backplane of the package can serve asthe power allocation request line 301.

(2) Rack Server System

The present invention can be implemented to control servers installed inracks of the rack server system by way of the rack management module,wherein the backplane or cable can serve as the power allocation requestline 301. In addition, the present invention can be implemented tocontrol the total power of the blade server packages installed in racks.

Lastly, it is apparent that the present invention is not limited to theabove embodiment, but may be modified and changed without departing fromthe scope and spirit of the invention.

1. In a power distribution system in which a plurality of informationprocessing apparatuses, undergoing fluctuations of power consumption andperformance owing to a power mode being set, is connected to amanagement module, for allocating power to the plurality of informationprocessing apparatuses, via a network, said power distribution systemcharacterized in that when the information processing apparatus needssurplus power allocation, the information processing apparatus sends apower allocation request to the management module so that the managementmodule sends back a power allocation response to the informationprocessing apparatus via a communication line, wherein the managementmodule includes a first control calculation unit and a first storageunit, wherein the first storage unit stores an allocated powermanagement table, which describes an upper-limit value of power entirelyallocated to the plurality of information processing apparatuses and anallocated power allocated to each information processing apparatus, anda power pool unallocated to any one of the information processingapparatuses, wherein the information processing apparatus includes apower sensor measuring real power consumption, a second controlcalculation unit, and a second storage unit, wherein the second storageunit stores the power mode, a power mode management table describing amaximum power value for each power mode and an upper mode requestthreshold for requesting transition to an upper power mode, theallocated power, and redundant power, wherein the second controlcalculation unit calculates the redundant power based on a differencebetween the allocated power and the real power consumption, thusupdating the redundant power stored in the second storage unit, whereinthe first control calculation unit collects the redundant power and addsit to the power pool, wherein when the information processing apparatusrequests additional power allocation, the first control calculation unitallocates a part of or the entirety of the power pool to the informationprocessing apparatus, wherein the second control calculation unitchanges the power mode in response to the allocated power, wherein thefirst storage unit stores a pool threshold representing a lower-limitvalue of the power pool, and wherein the first control calculation unitcollects the redundant power only when the power pool is below or equalto the pool threshold.
 2. The power distribution system according toclaim 1, wherein the communication line is configured of a plurality ofbits.
 3. The power distribution system according to claim 1, wherein thepower sensor measures real power consumption during a predeterminedpower monitor time, and wherein the second control calculation unitdetects a power monitor value corresponding to a maximum value withinthe real power consumption measured during the predetermined powermonitor time, thus calculating the redundant power based on a differencebetween the allocated power and the power monitor value.
 4. A powerdistribution method for allocating power to a plurality of informationprocessing apparatuses undergoing fluctuations of power consumption andperformance owing to a power mode being set, said power distributionmethod characterized by comprising the steps of: storing an allocatedpower management table, describing an upper-limit value of powerentirely allocated to the plurality of information processingapparatuses and an allocated power allocated to each informationprocessing apparatus, and a power pool unallocated to any one of theinformation processing apparatuses; storing the power mode, a power modemanagement table, describing a maximum power value for each power modeand an upper mode request threshold for requesting transition to anupper power mode, the allocated power, and redundant power; calculatingthe redundant power based on a difference between the allocated powerand real power consumption, thus updating the stored redundant power;collecting the redundant power and adding it to the power pool;allocating a part of or the entirety of the power pool to theinformation processing apparatus when the information processingapparatus requests additional power allocation via communication line;changing the power mode in response to the allocated power via thecommunication line; and storing a pool threshold representing alower-limit value of the power pool, wherein the redundant power iscollected only when the power pool is below or equal to the poolthreshold.